Question

a child of mass 50 kg is standing on the edge of a merry go round of mass 250 kg and radius 3.0 m which is rotating with an angular velocity of 3.0 rad sâ’1 . the child then starts walking towards the centre of the merry go round. what will be the final angular velocity of the merry go round when the child reaches the centre?

Answer 1

Iω = CONSTANT

Therefore I1ω1 =I2ω2

where I is moment of inertia , I =mr∧2

ω2=I1ω1/I2

    =300 3∧2×3/250×3∧2  (as boy weight is at centre so the only weight is of merry go round)

    =6/5 rad/sec